The chemical composition of the lipopolyacarideof Pseudomonas aeruginosa.

1. Lipopolysaccharide was isolated from both cell walls and acetone-dried whole cells of Pseudomonas aeruginosa (N.C.T.C. 1999). 2. Closely similar products are obtained, although that from whole cells cannot be completely freed from small amounts (2-7%) of residual nucleic acids. 3. The lipid moiety (23-33%) has a similar amino sugar backbone to that of lipids of enterobacterial lipopolysaccharides, but contains different hydroxy acids (2- and 3-hydroxydodecanoic acid and 3-hydroxydecanoic acid). 3-Hydroxytetradecanoic acid is absent, and 3-hydroxydodecanoic acid is the main N-acylating acid. No clear evidence permitting a distinction between the possibilities that phosphodiester or glycosidic linkages exist between the glucosamine residues was obtained. 4. Identifiable sugars (glucose, rhamnose, 3-deoxy-2-octulonic acid and heptose) account for less than 20% of the lipopolysaccharide, and alanine, galactosamine and fucosamine are apparently components of the polysaccharide moiety. 5. The polysaccharide moiety is unusual in that it is not readily obtained from the lipopolysaccharide by treatment with dilute acetic acid, which does, however, solubilize much of the phosphorus of the lipopolysaccharide. 6. The ;polysaccharide' fraction (approx. 21%) obtained by treatment with dilute acetic acid contains only a small proportion of the total polysaccharide components, and in one case only 45% of the fraction was accountable for in terms of identifiable components. 7. Evidence suggests that unidentified nitrogenous components are concentrated in the residual material after removal of both the lipid and the ;polysaccharide' fraction from the lipopolysaccharide.